The altitudinal gradient pattern of mountain biodiversity and its formation mechanism are hot topics in ecological research. The altitudinal variations of belowground invertebrates are less understood than aboveground plants and animals. With soil mites as the model soil animals, we investigated their distribution patterns from 1318 m to 2500 m above sea level in three mountains of Lyuliang Mountains based on species diversity and functional diversity. We used soil pH, total N, total P, total K, and organic matter content to identify potential drivers of soil mite communities and diversity along the altitudinal gradient. A total of 715 soil mites were collected, belonging to 3 orders, 27 families, 28 genera, and 29 species. Phthiracarus clemens, Geolaelaps praesternalis and Diapterobates humeralis were dominant mites. Non-metric multidimensional scaling showed that soil mites community composition varied significantly among different altitudes due to Epilohmannia ovata predominated in high altitude and P. clemens predominated in middle altitude. There were significant differences in individual density of soil mites among different altitudes. The Margalef, Shannon, and Simpson indices followed a unimodal distribution pattern along the altitudinal gradient. Functional richness and functional evenness showed a unimodal distribution pattern along the altitudinal gradient, while other functional diversity indices changed little with altitude. The RDA results indicated that total K and soil pH were the major drivers for the variations in soil mite communities. The Pielou index of soil mites was significantly positively correlated with soil pH, while functional evenness was negatively correlated with altitude. Individual density, species number, Margalef, Simpson and Shannon indices were significantly positively correlated with functional richness index. Species diversity and functional diversity of soil mites varied differently with altitude. In the future, we should strengthen long-term monitoring and dynamic functional properties of soil mites and the community assembly to deeply understand the relationship between biodiversity and ecosystem functions.
山地生物多样性的海拔梯度格局及其形成机制一直是生态学研究的热点问题。然而,目前的研究多集中于地上植物和动物,关于地下无脊椎动物的研究明显具有滞后性。本研究以土壤螨类这一典型的中型土壤动物为研究对象,采用梯度格局法,对吕梁山自海拔1318 m至2500 m,每隔约100 m进行土壤样品采集,共9个海拔,采用物种多样性指数和功能多样性指数探讨土壤螨类多样性沿海拔梯度的分布格局。同时,测定土壤pH、全氮、全磷、全钾以及有机质含量,探究土壤螨类多样性对环境因子的响应机制。本研究共捕获土壤螨类715只,隶属于3目27科28属29种,小枝卷甲螨、胸前下盾螨、肩翅尖棱甲螨为优势种。非度量多维尺度分析结果表明,土壤螨类群落结构沿海拔梯度变化明显,主要是由圆上罗甲螨、小枝卷甲螨分别在高海拔地区和低海拔地区的集中分布造成的。单因素方差分析结果表明: 不同海拔间土壤螨类个体密度具有显著差异,Margalef指数、Shannon指数、Simpson指数沿海拔梯度的变化呈单峰分布格局,在中海拔处达到最大;土壤螨类的功能丰富度指数和功能均匀度指数随海拔的变化呈单峰分布格局,其他功能多样性指数随海拔变化无明显变化规律。冗余分析结果表明,全钾和土壤pH是影响土壤螨类群落组成及分布的主要环境因子。土壤螨类Pielou指数与土壤pH呈显著正相关关系,土壤螨类功能均匀度指数与海拔呈显著负相关关系;个体密度、物种数、Margalef指数、Simpson指数和Shannon指数均与功能丰富度指数呈极显著正相关关系。土壤螨类的物种多样性和功能多样性对海拔高度的变化有不同的响应规律,未来应加强长期动态监测,以深入探讨土壤生物多样性与生态系统功能的关系。.
Keywords: altitude gradient; functional diversity; soil animal; soil mite.